1. Field of the Invention
The instant invention relates, generally, to ceramic structures. More specifically, the present invention relates to composite materials which are structurally reinforced by a ceramic matrix material.
2. Description of the Prior Art
There are known in the ceramic arts open-cell or open-pore ceramic foams which are primarily used as filter media. Because of the high compressive strength of ceramic materials and their three dimensional repeating dodecahedral structure, these foams have been proposed as ceramic skeletons for composite structural material such as in Applicant's prior application Ser. No. 07/542,778, filed Jun. 25, 1990, the disclosure of which is hereby incorporated by reference.
The composite structural members of the prior application use a ceramic foam dodecahedral skeleton with either hollow or solid legs as a reinforcing matrix. The ceramic foam is used because of its low weight, high compressive strength and low cost. However, the brittleness of the foam is a drawback.
Therefore, to form the structural members, a polymeric filler is normally used to saturate the ceramic skeleton and to overcome the brittleness handicap. Other materials may be used other than polymers to saturate the ceramic skeleton as long as they can withstand the destruction process that is performed on the ceramic skeleton without the filler.
Although the ceramic open-cell foam dodecahedral skeleton or matrix provides a strong reinforcement for composites, its strength is not consistent throughout the structure. This is due to the random nature of the dodecahedral structure. While the matrix structure exhibits a high degree of variation in cell size, position, and filament length and cross-sectional area, the resultant structural strength of each cell is variable and unpredictable.
The load bearing capabilities of a composite using a ceramic foam as a matrix are further compromised by discontinuities in the cells and interruptions in the off-limits that make up the cells. Because the strength of the reinforcement structure is variable, it can only be determined within a range through the use of statistical methods of approximation. This limits the design capabilities of the structure.
Thus, it is desirable to provide a ceramic reinforced composite that capitalizes on the inherently high compressive and tensile strength of the ceramic materials and permits an accurate prediction of the strength of the ceramic reinforced composite. This provides for more flexibility in designs of application. It is to this to which the present invention is directed.